Method of and apparatus for transmitting motion pictures



Oct. 7, 1930. 'c. F. JENKINS Filed June 22 1927 Patented Oct. 7, 1930UNITED STATES PATENT OFFICE.

CHARLES FRANCIS JENKINS, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNORTO JENKINS LABORATORIES, OF WASHINGTON, DISTRICT OF COLUMBIA, A CORPORA-TION OF THE DISTRICT OF COLUMBIA METHOD OF AND A'EPPARATUS FORTRANSMITTING MOTION PICTURES Application filed June 22, i927. Serial No.200,751.

My invention relates to a method of and apparatus for electricallytransmitting a series of pictures varying slightly from each other, suchas the pictures found on a motion picture film, and projecting thesepictures upon a screen at a rate to produce persistence of Vision.

An object of my invention is to produce apparatus whereby pictures maybe transmitted from .a continuously moving picture film and projectedupon a stationary screen without the employment of light shutters suchas is commonly employed in standard motion picture projecting machines.-

My invention contemplates the transmis sion of pictures from acontinuously moving filmby analyzing the pictures thereon intoelementary areas, and projecting the light variation from successiveelementary areas upon a stationary screen in positions corresponding tothe positions occupied by the elementary areas in the pictures on thefilm.

Another object of my invention is to transmit motion pictures from acontinuously moving film by scanning the film in a directionsubstantially at right angles to its movement to thereby analyze thepicture into elementary areas, transmitting the light variations fromthe successive elementary areas to a stationary screen and projectingthe successive light variations upon the screen at points correspondingto the position of the elementary area being scanned with respect to itspicture area on the moving film.

More particularly my invention contemplates transmitting pictures from acontinuously moving film by analyzing each successive picture area intosuccessive elementary areas, translating the light variations from thesuccessive elementary areas into like electric variations, translatingsaid electric variations into like light variations, projecting thelight variations upon a stationary screen, and distributing theprojected light variations to points on the screen corresponding inpositions to the positions occupied by the respective elementary areasof the picture being transmitted from the film,

Another object of my invention is to devise apparatus for carrying outthe foregoing method of transmitting motion pictures.

In the operation of my invention the trans- 'necting the transmittingand receiving stations.

My invention is illustrated in the accompanying drawing in which Figure1 illus trates diagrammatically one form, of the ap: paratus employed atthe transmitting station; and Figure 2 illustrates diagrammatically oneform of apparatus which may be employed at the receiving station.

Referring to Figure 1 of the drawing, a standard motion picture film Fis driven at a constant rate by a sprocket wheel W. Film F has beenshown with its plane at right angles to the plane of the drawing. On oneside of the film, a lamp L provided with an ellipsoidal reflector R,disclosed in my Patent 1,390,445, is arranged to illuminate the pictureson the film as they pass in front of the lamp. On the other side of thefilm, a rotatable disc 1) of opaque material, and provided with aplurality of like lenses N mounted in holes formed near its outer edge,is arranged to rotate in front of the film in a plane parallel to theplane of the film. Disc D isso positioned that lenses N will rotate infront of the lighted portion of film F substantially at right angles tothe direc tion of motion of the film. A light sensitive cell C providedwith a housing H is located in optical alignment with light L, film F,and

lenses N. Lenses N are all alike and serve to form enlarged images ofthe illuminated portion of film F in the plane of the front wall ofhousing H as they are rotated in front of the film. The housing of cellC is provided in its front wall with an aperture (a) for admitting tothe cell light from a small portion of the image projected upon thehousconstruction, preferab ing by a lens N. The light sensitive cell isprovided with an energizing battery B and a regulating resistance R Thecell C may be of any well known type, preferably, a potassium cell. Thiscell may be connected either to a carrier wave transmitting apparatus Tor directly to a line circuit L by means of switches S and S Thetransmitting apparatus may be of any suitable having a vacuum tubegenerator of high requency waves with suitable means for modulating theenerated wave b the current variations su p ed from the lig t sensitivecell. It is o vious' that instead of radiating the carrier wave to thereceiving station, it may be wired to the receiving station by connectinthe output circuit of transmitter T to line I At the receiving stationshown in Figure 2, D indicates a radio receiving set of suitableconstruction for the purpose of receiving the modulated radio wavesradiated from the transmitter T. The output of the receiving set D maybe supplied to the in ut of anamplifier A by means of switches and S. Agaseous lamp L is connected to the output circuit of am lifier A. Pindicates a screen upon which is e pictures are to be projected. Locatedbetween screen P and lamp L is a scannin device for distributing thesuccessive lig t variations upon the screen I in their correct order andcomprises the rotating disc D provided with a plurality of like lensesmounted in holes formed near its outer edge, and a rotating prismaticring PR. Lenses N on disc D form im s of the lighted lamp L upon thesurface 0 screen P. Ro tation of disc D will, therefore, cause asuccession of images of the light source L to sweep across screen P. Therays which form the image of lamp L pass through the outer edge of theprismatic ring PR, and are refracted in a vertical plane by an amountdependent upon the an le between the faces of the prismatic edge 0 thering. Accordingl if prismatic rlng PR be caused to rotate, the anglebetween the faces of the prismatic portion of the ring'at the pointwhere the rays pass through 1t will be varied, and the successive imagesof lam Y L will be caused to traverse screen P by different paths.

The operation of my invention is as follows:

Film F is moved at a constant rate by wheel W so that from 10 to 16pictures pass a given Boint per second. Lenses N, on rotating disc formenlarged images of the lighte portion of the film F upon the li htsensitive cell (1.. Due to the rotationvo disc 'D these images arecaused to sweep successivel across cell C, and since film .F is constanty moving downwardly, the successive images crossing 0011- C, I resentnew areas of the picture surface 0 film F before the aperture (a) inthe. cell housing H. In other words, the effect is the same as if thefilm were drawn upwardly in front of cell C at a rate of from 10 to 16pictures per second and simultaneously were given rapid transversescanning motions in order to scan the picture area 'in successiveparallel lines at right anles to the direction of motion of the film.

nly a small portion of each image area is admitted to the cell throughthe aperture of the cell housing, accordingly, the cell views, or scans,only a narrow transverse strip of each. image as it passes in front ofthe housing. The speed of lens disc D is adjusted so that the successivestrips of exposure to the cell lie adjacent each other and substantiallythe entire picture surface is scanned. For example, assume that theaperture ((1) scans a strip only 1/50th of the height of the image, inorder to scan every portion of a sing e picture it will be necessary tocause 50 images of that picture to sweep across the cell during the timeit takes the picture to travel in a vertical direction past theaperture, and if 16 pictures are passing theaperture in a Verticaldirection per second it will be necessary to cause 16 50, or 800 images,of the movin filmto traverse the cell per second. In ot er words, thespeed of disc D in revolutions per second will be 800 divided by thenumber of lenses mounted on the disc. It is to be understood that thedisc may be rotated either faster or slower than above described, but ifrotated slower the quality of reproduction will be inferior for thereason that the exposure strips will be spaced apart. I find itconvenient to drive film F and disc I) synchronously and fromthe samesource of power, although it is obvious that this is not necemary. I

The cell C is affected in a well known manner by the light variationsimpressed upon it to produce a current varying in amplitude inaccordance with the light variations of the successive elementary areasof the picture. In case it is desired to transmit over great distancesthis varying current may be used to modulate the current radiated fromthe transmitting station'T by arranging switches S and S to connect withthe central contacts. Instead of transmitting the current variationsfrom cell C to the receiving station in the form of a modulated carriercurrent, it may be transmitted in its original form di rectlyl to thereceiving station over lines L 2 by connecting switches S and S to theouter contacts. t the receiving station, waves received from transmitterT are detected by detector D to derive therefrom a current correspondingto the current produced in the circuit of cell C. This current issupplied to the input circuit of amplifier A where it is amplified andemployed to operate lamp L connected in the output circuit of theamplifier. In case the current from cell C is transmitted directly overlines llt) L' L to the receiving station, switches S and S are arrangedto connect amplifier A directly to the line to receive and amplify thecurrent transmitted directly from the cell circuit. Accordingly, lamp Lwill vary in intensity in accordance with the light variations impressedupon cell C at the transmitting station. Lenses N on disc D serve toconcentrate light from lamp L and form images of the filament of the.lamp upon screen P as they rotate in front of the lamp. Rotation of discD causes these images to sweep across the screen. Rotation of prismaticring PR will cause these images to traverse screen P at a higher orlower level depending upon the angle presented between the faces of theprismatic portion of the disc. It is obvious that for one rotation ofprismatic ring PR, the successive images are caused. to traverse screenP in all positions from top to bottom or vice versa, of the screen P.Disc D is driven in synchronism with disc 1) at the transmittingstation, and prismatic ring PR is driven in synchronism with the movingfilm F. These elements may be maintained in synchronism by separatesynchronizing system, but I find it convenient to drive both rotatingelements at each sta-- tion from a common source of power, and to use asingle system to synchronize the two sources of power. Any suitablesystem may be used, for example, I may use the system disclosed in my U.S. Patent No. 1,525,553, granted February 10, 1925, for automaticallymaintaining synchronism between the two operating motors, or I maymaintain synchronism by manual control, and employ the system disclosedin my U. S. Patent No. 1,537,- 088, to indicate the condition ofsynchronism. I may also employ any of the systems, either manual orautomatic, disclosed in my copending application Ser. No. 130,282, filedAugust 19. 1926.

It is apparent that prismatic ring PR not only must be maintained insynchronism with the movement of film F, but must also be maintained inproper phase relationship with the movement of the pictures into thescanning region. That is, as a picture on the film comes into posit-ionsuch that the cell begins to scan it, prismatic ring PR must be in aposition to project the rays from lamp L either to the highest or to thelowest position on screen P, depending upon whether the image of thepicture traversing the cell is erect or inverted. Also, the direction ofrotation of disc D must be such that the successive light variationsfrom lamp L are projected upon the screen in the same order that theyoccupied on the original object. It is apparent that by properlychoosing the direction of rotation of the various optical elements inthe system the pictures on the film may be properly projected upon thescreen regardless of the position which the pictures occupy while beingscanned, that is, they may be erect, inverted, or reversed as they passthrough the scanning apparatus.

The prismatic ring PR is constructed in accordance with the disclosurein my U. S. Patent No. 1,385,325, granted July 19, 1921. It consistsessentially of a disc of glass or other suitable materialhaving itssides near the periphery so shaped or ground as to form a ring shapedprism with the angle between its sides varying progressively around theperiphery of the disc.

Referring' to Figure 2 of the accompanying drawing, in the positionshown, the angle between the sides of the prismatic edge of the disc issuch that the rays from lamp L are refracted to the lowermost positionon the screen as showrrin light solid lines. As the ring is rotated inthe direction of the arrow for 180 degrees the angle between the sidesof the prism decreases until the sides are parallel, as shown at thelower edge of the disc in Figure 2, and the rays from lamp L will passthrough the ring without being refracted as shown by the broken lineswith long dashes. the angle between the sides of the prismatic ringbecomes reversed from that in the first 180 degrees of rotation andincreases progressively until just short of 360 degrees it has an angleindicated in dotted lines at the top of the disc in Figure 2. In thisposition, the rays from lamp L will be refracted to the uppermostposition on screen P as shown by the broken lines with short dashes. Itwill readily be appreciated that'more than one prism section may beformed on one disc and the speed of the disc adjusted so that the prismsections rotate past lamp L in synchronism with the passage of thepictures of film F in front of light L.

Disc D may have the same number of lenses as disc D in which case theywill rotate synchronously, but if the discs have different numbers oflenses their speed will be inversely proportional to the number oflenses on each disc, that is, the speeds will be such that each discwill cause the same number of lens to pass a given point in the sametime.

It will be understood that since film F is moving at a rate of 10 to 16pictures per sec- 0nd, and each picture is being completely analyzed,transmitted and projected upon screen P during the time it passes agiven point, the effect upon the eye will be a complete pictureprojected upon screen P every fraction of a second, and since eachsucceeding picture varies from the next, the final eifect will be thesame as that observed in the ordinary projection of moving pictures.

While I have shown one form of scanning apparatus employed at thetransmittin station, it is readily apparentthat other orms may be used.For example, instead of form- Upon further rotation of the disc Ina ingan-image of film F directly upon the cell C b lenses N, I may first forman image of the film and then form an image of this image upon cell C bylenses N, such an arrangement being disc osed in my U. S. Patent No.1,559,437, issued October 27, 1925. The specific form of lightdistributing apparatus employed at the. receiving station constitutesthe subject of my U. S. Patent No. 1,530,463, issued March 17, 1925. Itis obvious that other forms may be used, for example, I may use thedouble prismatic ring arrangement disclosed in my U. S. Patent No.1,544,156, issued June 30, 1925, and for a greater degree of refinementI may use the double prism shown in my Patent No. 1,618,090. Y

While my invention disclosed herein is particularly useful intransmitting motion pictures from a film between points distantlyremoved, it will be appreciated that both the transmitting and receivingapparatus may be placed in the same projecting booth and the system usedto project motion pictures upon a stationary screen from a continuouslymoving film without the use of so called rectifying devices tocompensate for the movement of the film.

What I claim is 1. The method of projecting pictures from a continuouslymoving film upon a stationary screen which comprises positioning a lightsensitive cell in front of said film, positioning a light bafiie infront of said cel illuminating a relatively large area of said film,projecting amagnlfied image of each elemental area of the film insuccession on said bafile to produce corresponding currents in saidcell, translatin said currents into a corresponding modu ated lightbeam, and moving said beam across said screen in'synchronism ,with thesuccessive projections of light on "said cell.

2. The method of projecting pictures from a continuously moving filmupona station ary screen which comprises positioning a light sensitive cellin front of said film, illu minating a relatively large area of saidfilm, interposing a perforated light bafile plate in front of said cell,roducing in succession magnified images of the elemental ortions of theilluminated area, moving sai images across said bafile to produce corresnding currents in said cell, rojecting a lig t beam upon said screen, moulating said beam, and spacially dis lacing said beam in synchromsm witht e movements of said image across said cell.

3. The method according to claim 2, in which each of said images issimultaneously moved in mutually perpendicular direction acrosssaidbafile plate.

4. In combination a picture film, a light sensitive cell, a stationaryperforated light bafile between said film and said cell, means forilluminating a relatively large area of said film, means forcontinuously bringing successive stri s of said film into opticalalignment 'wit said bafiie, means for projecting a magnified image ofadjacent elemental portions of each strip upon said cell through saidbafile to roduce corresponding current variations a xed screen, meansfor rojecting a light beam on said screen, means or varying theintensity of said beam in accordance with said currents, and means fordisplacing said beam in synchronism with the rojections of light-on saidcell to repro uce the image.

5. The combination according to claim 2 in which the means forprojecting the magnified images of the elemental portions of each stripincludes a lens continuously moving substantially at right angles to thefilm movement.

6. The-combination of a motion picture film, means for givinglongitudinal movement to said film, a stationar light sensitive cell, aperforated light ba e between said film and said cell, means forproducing magnified images of successive elemental areas of the filmupon said baflie, means for giving transverse movement to said images toproduce corresponding electric variations in said cell, a stationaryscreen, and means controlled by said currents for reproducing the motionpicture on said screen.

7. The combination according to claim 6 in which the film is movedcontinuously in a longitudinal direction.

8. The combination of a motion picture film, means for givinglongitudinal movement to said film, a stationary light translatingdevice, a perforated li ht bafile plate between said device and saidforming magnified images of the successive elemental areas of the filmupon said baflie, means for moving said images transversely over saidbafile, and at an angle to the direction of motion of film, a stationaryscreen, and means controlled by the response of said device forreproducing the motion picture on said stationary screen.

9. The combination according to claim 8 in which the film is movedcontinuously in a longitudinal direction. I

10. The combination of a picture film, means for givin continuouslongitudinal movement to said film, a stationary light translatingdevice, a stationary erforated plate between said device and saidpicture, a pluralit of devices for forming magnified images portions ofthe picture upon said baflie, a movable carrier on which sald imageforming devices are ilflounted, means for moving said beam over saidscreen, and means for simultaneously modulating said beam in accordancewith the shades of the elemental areas of the picture to be projected onsaid screen.

1m, means for 11. In a system for transmitting motion pictures, meansfor continuously moving the motion picture film, means for scanninsuccessive elemental areas of successive strips of the film, andincluding a movable lens for producing magnified images of saidelemental areas, a light sensitive device, a light baflle for selectinga portion of each magnified image and projecting it on said device, alamp for formin a reproducing l1 ht beam, means controlled y theresponse 0 said device for varying thebrilliancy of said lamp, astationary screen, means for focusing the light from said lamp upon saidscreen, and means for moving said llght beam over said section toreproduce the ictures.

In testimony w ereof I have aflixed my signature.

CHARLES FRANCIS JENKINS.

